In the threaded union for tubulars, a threaded male end on one of the tubulars is received by a female nut supported on a shoulder formed on or supported by the other tubular. The threaded union is a commonly used and popular connector for joining tubulars in a wide variety of applications because it is relatively inexpensive to manufacture and permits rapid end-to-end connection of two tubulars without axial rotation of either tubular. While threaded unions are popular, they generally lack the holding strength of a flanged connection. This is due to either of two factors, namely: the nut is dissected in two parts that are welded together after the nut is positioned above a shoulder that supports it; or, the top flange of the nut is weakened because it is reduced in width to accommodate a multi-part collar that provides the shoulder for supporting the nut. In high-pressure fluid applications the strength of a threaded union is critical. This is especially true in the oil and gas industry where tubulars are often subjected to severe mechanical stresses as well as extreme fluid pressures of 20,000 psi or more.
Therefore there exists a need for a threaded union for tubulars used in high-pressure fluid applications.